The designer of a wire stripper machine is conventionally faced with 2 major technical requirements: driving an insulated wire through the machine and making a cut on the wire insulation. The two main means of guiding the driving of a wire are an adjustable one-hole (one-hole-fits-all) guide and a nonadjustable hole, or minimally adjustable multiple-hole guide means. Either means may apply to single-entrance wire strippers and multiple-entrance wire strippers. There are also less common strippers that sit in between the two machine types. Although it drives wire better, a multiple-hole type wire stripper machine has disadvantages, such as higher cost, size, and weight. Therefore, there has been a long felt need in the market for an adjustable one-hole stripper machine with improved wire driving performance.
An adjustable, one-hole stripper machine must be able to fit wires ranging from a very small diameter (e.g. 1 mm) to a very large diameter (e.g. 75 mm). Its wire drive wheel must also have good contact with the wire in order to provide sufficient traction and to fix the wire at a desirable location. Typically, instead of the circular shaped opening frequently used in multiple-hole strippers, a V-shaped wire drive wheel is used in adjustable-hole strippers. The V-shaped wire drive wheel allows wires with any diameter to sit at its center point or trough, directly under the blade. With the blade at an appropriate height, a continuous longitudinal cut can be made as the wire is driven through the stripper machine.
However, one of the main difficulties with the V-shaped wheel is a poor wire retaining capability. In practical application and operation, the wire can often escape from the ideal location in the center line of the V-shaped wheel directly under the blade. The wire may escape when it is not perfectly straight (w/bends and kinks), the wire is thin and soft (easily deforms its shape and gets pushed aside by the blade) and the wire is slippery and/or stiff (higher blade pressure needed), which in turn generates greater side-shoving force when the wire is not centered in the trough. The wire may also escape from the ideal location when the blade is slightly dull and requires greater downward pressure.
FIG. 1 is a close up view of a wire stripper machine common to the prior art, including a rotary cutting blade on a shank and a V-shaped wire drive wheel on a turn crank shaft. The shaded open area shows a wide open possible escape route for the wire in the prior art. As a result, adjustable-hole strippers are typically not well suited for thinner and/or softer wires. A lot of techniques have been tried in the prior art to keep the wire at the center. Some examples are an input plate which restrains the wire at a distance (e.g. 2″) from the blade, an input tube which inserts into the hole on the input plate and restrains the wire at a closer distance (e.g. ½″) from the blade.
None of the prior art solutions can offer satisfactory results because they don't offer restrictions at the critical plane that is perpendicular to the blade, and includes the blade center and the axis of the V-shaped wheel, where wire escape takes place. Therefore, the long felt need in the market for an adjustable one-hole stripper machine with improved wire driving performance has gone unmet until the Applicant's present disclosure.